1. Field of the Invention
The present invention relates to a vehicle drive motor that may be used as a drive source in various motor driven vehicles such as, for example, automotive vehicle and railroad vehicles.
2. Description of Related Art
The vehicle drive motor, particularly the drive motor used as a drive source in an electric car or a hybrid car is required to have not only a compact and lightweight feature, but also a capability of providing the maximum output for energy saving purpose. Where a high power motor is desired to be downsized, a major problem arises as to how the heat emission resulting from a loss thereof is alleviated. In this kind of the vehicle drive motor, an attempt has been made to use a system of cooling the motor rotor with a lubricant oil.
[Patent Document 1] JP Laid-open Patent Publication No. H09-154258